Direct Monitoring of In Situ and In Vitro Nitric Oxide Release in the Brain during Malaria Infection with Plasmodium berghei N/13/1A

Abstract

Abstract

Clinical manifestations of cerebral malaria (CM) involve sequestration of cerebral capillarieswith red blood cells, brain hemorrhage, mental disturbance and coma. In addition to numerouscytokines involved in the immune response, nitric oxide (NO) has been shown to be produced inmalaria. This tiny molecule with a short half-life acts as a signal in cells or kills pathogens. Despitethe importance of NO as a biological mediator, few methods have been described for its assay.Electrochemical detection (ECD) is sensitive and has to be applied at the site of NO production;however, Griess microassay (GMA) is less sensitive and measures NO metabolites (nitrite, nitrate).The ability of the brain to produce NO was investigated here for the first time by in situ and in vitroNO direct detection in the brains of the terminally-anesthetized P. berghei N/13/1A-infected MF1mice. The ECD assay measures NO with continuous direct monitoring using a NO-selective electrode.The sensitive probe measures the concentration of NO in soft tissues at nanomolar (nM)concentrations. ECD results showed a rise in the brain NO in malarial mice (P < 0.01) in both in situand in vitro ECD. The increased level of NO in P. berghei N/13/1A-infected mice suggests its criticalrole in host defence and in the brain as a possible target organ. Some key points, including the typeof brain tissue, the variation of cell types, and the function of each cell, require further studies toclarify the specific function of the brain as a target organ in CM.

Keywords: brain, cerebral malaria, CM, nitric oxide, NO